MiraZyme: How to Remove Mildew from Backpacking Gear

Mildew spots on the hip belt and back of a winter backpack
White mildew spots on the hip belt and back of a winter backpack

Whenever you get back from a hiking and backpacking trip, it’s important to hang up your tent, backpack, footprint and other gear and let it dry off so that mildew doesn’t form on it. But mildew can also grow on gear that is stored in a damp place like your garage or basement, so you need to inspect your gear periodically to make sure you don’t have a problem.

Besides imparting a musty smell, mildew breaks down the materials in backpacks, tents, sleeping bags. bivy sacks or other backpacking gear, weakening them and making them more prone to rips and holes. You’ve probably spent some serious money buying this gear and its pays to take care of it.

Black Mildew Spots on a Bivy Sack
Black Mildew Spots on a Bivy Sack

Signs of Mildew

Mildew manifests itself as white or dark spots and can occur on all fabric types ranging from canvas and pack cloth to and polyester and silnylon. If you do nothing to treat mildew, it will eventually digest the clothing or gear it’s growing on and ruin it. As mildew spreads, it can also leave a stain on your gear and clothing which can be difficult to remove.

Stop Mildew from Spreading

In order to salvage mildewed gear, a simple first step is to stop the mildew from growing further. Move the gear to a dry location and expose it to sunlight. This will retard its spread until you can get around to killing the mildew and removing it permanently. Be careful not to expose the mildewed items too long to bright sunlight because the UV can also degrade or bleach colored fabric over time.

Mirazyme - Odor and Mildew Eliminator
MiraZyme – Odor and Mildew Eliminator

Kill the Mildew Dead

When you’re ready to get rid of the mildew that is left on your gear, your best bet is to use an enzyme cleaner like MiraZyme which will kill the mildew, clean the item, and eliminate the mildew smell. Mirazyme contain enzymes and microbes that kill mildew and eliminate odors. It’s also commonly used on wet suits, Gore-tex dry suits, and sandals to remove bad smells and funk.


1. To use MiraZyme, fill your bathtub or a plastic container with water and add 1/2 ounce (two capfulls) for each 20 gallons of water. Keep the water luke warm – not too hot and not too cold.

2. Dip the mildewed item in the MiraZyme solution and let it soak for 15 minutes. For backpacks, open all of the zippers and compartments so they get soaked. The same with sleeping bags, bivy sacks, tent bodies, technical jackets, sweaters, etc.  You can also fill a spray bottle with the MiraZyme solution and spray it onto the item, soaking the affected area. Dipping is preferable over using a washing machine because the agitation is likely to tear delicate items or ones with lots of straps. Dunk the itema  few times to make sure that all the trapped air escapes and that all of its surfaces get wet.

Soak in a tub of Mirazyme solution for 15 minutes
Soak in a tub of MiraZyme solution for 15 minutes

3. Soak in the MiraZyme solution for 15 minutes.

Drip Dry (in the basement)
Drip Dry (in the basement)

4. Remove the item and drip dry. DO NOT RINSE!

Mildew is completely removed
Mildew is completely removed


It’s an astonishingly simple process and one which often eliminates all trace of the mildew from an item permanently, and because MiraZyme comes in a highly concentrated form, one bottle lasts a long time.

Disclosure: Philip Werner (SectionHiker.com) purchased this bottle of MiraZyme with his own funds. 
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  1. I’ve been using White Vinegar and water for years I obtained the method from my Grandmother and from my Mother. .Fill tub with cold water and two cups of Vinegar and immerse item for about 5 minutes. Empty tub, refill, rinse, hang in the Sun to dry..You might try reading a book on the many uses of Vinegar..there are about a dozen out there right now.

  2. Good Tip! I didn’t know Myrazime would kill mildew. Note that any staining/bleaching spots is likely permanent.

    • I freaked out when I found mildew on my winter pack. We sealed the floor of our basement over the summer and have a lot more humidity down there so I had to move all my gear upstairs. I’ve been using MiraZyme for years for wetsuits, so I was confident about using it on my pack and bivy, both which were handmade for me and irreplaceable.

  3. I used a solution of white vinegar and salt, wiping down the whole tent while pitched. Its dry now and you can feel the salt crystals. It didn’t say to rinse but I feel like I should, then let it dry again before packing it up for winter.
    Anybody use this salt and vinegar method and did you rinse?

    • Vinegar is acidic and will likely greatly weaken the fabric if not washed out. Thorough wash, to get it out of the seams.

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